Letter opener

ABSTRACT

LETTER OPENER HAVING A GUIDE GROOVE AND A KNIFE IN A HANDLE WITH A SPRING THEREIN SO THAT THE LATER CAN FORCE THE KNIFE INTO THE GROOVE AGAINST AN ADJUSTABLE STOP TO CONTROL THE EXTENT OF THE KNIFE PROJECTING INTO THE GUIDE GROOVE.

Nov. 16, 1971 v, F E R 3,619,902

LETTER OPENER Filed March 12, 1969 2 Shoots-Shoot 1 Fig. 1

Fig.3 3 2 8 3 7 16a 5 1 7 1 0 INVENTOR.

JOSEF V/KTOR FLEUR) Nov. 16, 1971 J. v. FLE URY ,5

LETTER OPENER Filed March 12, 1969 I 2 Sheets-Sheet 2 INVEN'IUR. JOSEF V/KTOR FLEURY 44/WMCOQI y 0 United States Patent 3,619,902 LETTER OPENER Josef Viktor Fleur-y, Rapperswil, Switzerland, assignor to Mewecco Fleury Mechanische Werkstatte Filed Mar. 12, 1969, Ser. No. 806,523 Claims priority, application Switzerland, Mar. 15, 1968, 3,914/ 68 Int. Cl. B26b 29/00 US. Cl. 30294 6 Claims ABSTRACT OF THE DISCLOSURE Letter opener having a guide groove and a knife in a handle with a spring therein so that the latter can force the knife into the groove against an adjustable stop to control the extent of the knife projecting into the guide groove.

The invention relates to a letter opener having a guide groove into which a knife projects from one side, with which an envelope drawn through the guide groove with the side that is to be opened, is cut open along said side and which, for the insertion of the side of the envelope that is to be opened into the guide groove, can be pulled out or pushed out counter to the action of a spring from said guide groove.

In a known letter opener of this type, the knife extends from one side of the guide groove to such a point into said guide groove, that the point of the knife will abut on the other side of the guide groove against the side wall of said groove. This known letter opener, however, has the disadvantage that the knife will become blunt relatively quickly at the point of said knife because after each time the knife is pulled out of the guide groove it will snap back under the action of a spring and will strike with its point against the side wall of the groove causing a more or less strong deformation of the knife point to be brought about. In this connection, one must consider that the pressure on the point of the knife whenever it strikes against the side wall of the groove is extremely great as long as the knife at its point is still sharp, because the support surface at the point of the knife is exceedingly small in the case of a very sharp point. If, for example, the spring pressure is 100 g./mm. and the supporting surface has a size of 0.1 mm. x 0.1 mm., then this will result in an impact pressure on the knife point, upon striking against the side wall of the groove, of 1000 kg./cm. therefore an extremely high impact load will lead to the deformation of the knife point even after a few impacts. If the supporting surface becomes larger as a result of the deformation, then the impact load will drop in correspondence with the increase of the supporting surface up to a value at which the impact load does not bring about deformation any longer. However with this increase in the supporting surface, the knife also becomes correspondingly more blunt at its point so that it will no longer cut at the point. An envelope, pulled through the guide groove, therefore, will not be opened at all in many cases because the knife point, resting on the envelope after said envelope has been inserted, is too blunt to penetrate the paper and therefore will leave only a scratch mark of its path during the withdrawal of the envelope. Also, a blunt knife point, having small jags as a result of a deformation, will be caught when it is drawn through so that it will tear the envelope open.

In order to avoid these disadvantages, a fixed stop has been provided therefor in the case of another known letter opener design, of the type mentioned in the foregoing, to prevent the knife from being able to strike with its point against the side wall of the groove. Although the problem 3,619,902 Patented Nov. 16, 1971 of knife point deformation was solved, another problem now arose. In order for the letter opener to function faultlessly, and in order also to be used for opening envelopes made of very thin paper, for example air mail paper, it was necessary to arrange the fixed stop in such a manner that the distance between the knife point and the side wall of the groove in the impact position of the knife would amount to 0.1 mm. maximum. And the distance between the knife point and the side of the wall of the groove in the impact position of the knife would amount to 0.1 mm. maximum. On the other hand, the distance between the knife point and the side wall of the groove in the impact position of the knife was not permitted to be less than 0.05 mm. for reasons of safety. Therefore, the tolerance for the position of the fixed stop was only outside the order of magnitude of 0.05 mm. This high requirement of tolerance necessitated a relatively high precision during production which, in turn, led to a considerable increase in production costs.

It is therefore an object of the invention to provide a letter opener of the aforementioned mentioned type wherein, but deformation of the knife point cannot occur which, however, can be produced without expensive and costly precision work. According to the invention, this will be achieved with a letter opener of the aforementioned mentioned type, that is, characterized by a shiftable stop which is adjustable with said stop in respect to the distance of the knife projecting into the groove. In such case the stop may be adjustable in such a manner for a particular advantage, in that the knife will project from one side of the guide groove through said guide groove and up to a recess provided on the other side of the guide groove in the groove side wall. At the same time the recess may effectively be a depression in the side wall of the groove, and the knife point may reach into the depression in the case of one limit of the stop which is adjustable, but which does not reach to the bottom thereof.

A particularly advantageous design of the present letter opener is that the knife is provided with an impact surface which is pressed against a disk made adjustable by turning, and mounted eccentrically to form the stop. The letter opener at the same time can be provided effectively with an elongated handle and with a guide groove running transversely in relation to the longitudinal direction of the handle at its front end, as well as with a shiftable knife inside the handle operable preferably by means from outside the handle. Also, the knife may be provided at its front end with one or more edges so as to be effective in both directions of the guide groove, and a compression spring may be disposed likewise at the rear end of the knife within handle and supported therein. Further the knife is provided with a recess developed preferably as an opening, whose rear edge surface forms the supporting surface and within which the eccentrically mounted disk has been disposed, and the disk is provided with at least one bearing pin which is mounted with a tight fit in the handle, with one bearing pin which can be rotated from the direction of the outside of the handle,

As a particular advantage, the knife furthermore may be doubled edged, so that it will cut in either of the two possibe directions of motion of an envelope through the guide grooves as for example, in such a shape that the knife at its front end has two edges meeting at the point of said knife and extending at an angle in relation to one another.

Further objects will be apparent from the following description when considered in connection with the accompanying drawings in which;

FIG. 1 is a bottom plan view of a letter opener according to the invention,

FIG. 2 is a cross-section through the letter opener taken on line I- I in the direction of the arrows of FIG. 1,

FIG. 3 is a top plan view of the parts of the letter opener of FIG. 1 with the cover plate partly cut away, and

FIG. 4 is a perspective exploded view of the parts of the letter opener.

The letter opener as illustrated, is comprised of a handle 1 which has been provided with guide paths 2 for the knife 3, a hole 4 for the compression spring 5 engaging at the rear end of the knife 3 and having a bearing point 6 for the disk 7 provided with two eccentrically disposed bearing pins 7a and 7b. A recess 8 is provided for insertion of the cover plate 9 and two threaded holes 10 are in the handle 1, for screwing on the cover plate 9. Furthermore, the letter opener is provided with the knife 3, the already mentioned spring 5, the disk 7, as well as the cover plate 9 and screws 11 for screwing down said plate on the handle 1, as well as a knob 12 that can be screwed onto the knife blade 3 in order to withdraw the knife.

The guide groove 13 of the letter opener into which the side of thet envelope which is to be opened is inserted, is formed by the cover 9 and the front end of the handle 1, that is the one side of the guide groove 13 into which the knife projects, from the front end 1a of the handle 1 and the bottom of the guide groove 13, as well as the other side wall 9a of the groove from the cover 9, which on its front end has been bent at a right angle. The knife 3 reaches from the side 1a into the guide groove 13 and it can be withdrawn from the guide groove 13 counter to the pressure of the spring 5 by means of knob 12 for the purpose of inserting the side of the enveope that is to be opened into the guide groove 13. The knob 12 has been screwed into the knife with a screw connection 12a in a threaded hole and it projects with its neck 1212 through a recess 15 in the plate 9. The recess 15 in the plate 9 is covered up by the head of the knob 12. The knife 3 has been provided with an opening 16, inside of which disk 7 has been disposed. The disk 7 has been mounted on the one hand, with the eccentrically disposed bearing pin 7a in the cylinder-shaped depression 6 in the handle 1 with tunking tit and, on the other hand, With the eccentrically disposed bearing pin 7b in the bore 17 in the cover 9 likewise with tunking fit. The hearing pin 7b on its face has a slit 70 into which a screwdriver can be inserted to turn the disk 7 and this disk constitutes the adjustable stop of the letter opener. The rear edge surface 16a of the opening 16 in the knife 3 constitutes the impact surface of the knife which is pressed by the spring 5 against disk 7 constituting the stop. The recess 15 in the cover 9 is of such length, that in the case of a complete turn of the disk 7 and of a reciprocal movement of the knife 3, caused as a result thereof, the knob 12 attached to the knife, will strike neither in front nor in the rear against the recess 15. In the drawing the disk 7 has been drawn in the position constituting the rear limit of the stop for adjustment. In the case of this position of the stop, the knife 3, as can be seen in FIGS. 1 to 3, will still reach with its point 3a into the guide groove 13, and this position is applicable, for example, for the opening of very thick letters. If the disk 7 is turned 180 degrees with the aid of a screwdriver engaging in slit 70, then it will be in the position constituting the front limit of the stop for adjustment. In that case the knife 3 reaches from the one side 1a of the guide groove 13 through said groove up to and into a recess 18 provided on the other side of the guide groove 13 in the side wall 9a of the groove, but it does not reach into its bottom thereof. The recess 18 can be made as large as is necessary, so that no special requirements concerning close tolerances will have to be made during the production of the letter opener. For practical purposes the front limit of adjustability of the stop can then be dimensioned in such a manner that the knife point 3a will project up to about half the depth of recess 18, into said recess if the dimensions of the individual parts have been maintained exactly, whereby then, the permissible tolerance is equal to half the depth of recess 18. In the present case, recess 18 has a depth somewhat greater than 1 mm., so that permissible tolerances of the front limit of adjustability of 0.5 mm. can be maintained Without difficulty and without involving any extensive precision work.

The knife 3, furthermore, has been provided with two edges 3b and 30, so that the envelope which is to be opened can be drawn in each one of the two possible drawing directions through the guide groove 13 and can be opened by this procedure.

The present letter opener, as compared to the letter openers previously known and mentioned hereinabove is designed as having the essential advantage, that, deformation of the knife point is impossible and thus also a blunting thereof and during production, no precision work must be accomplished so that the production costs can be minimized. Also, as the result of the two-edged knife, the device may be drawn in either of two possible drawing directions against the envelope through the guide groove, which is particularly advantageous for use by both right-handed or left-handed persons.

I claim:

1. A letter opener having a guide groove for the reception of the edge of an envelope to be drawn therealong comprising, a handle, a knife blade disposed within said handle and extending into said guide groove for cutting the envelope edge as it is drawn along said groove, said knife blade having a stop surface thereon, an adjustable stop comprising an eccentrically mounted disk in contact with said stop surface for controlling said blade extent into said groove, and a spring provided in said handle for urging said stop surface against said disk.

2. A letter opener according to claim 1 wherein said guide groove is defined by a side wall having a recess therein into which said blade may extend upon its full extension into said guide groove.

3. A letter opener having a guide groove for the reception of the edge of an envelope to be drawn therealong comprising, a handle, a knife blade extending into said guide groove for cutting the envelope edge as it IS drawn along said groove which is located at the front end of said handle extending transversely of the longitudinal axis of said handle, an adjustable stop within said handle for controlling said blade extent into said groove, a spring provided in said handle for urging said blade against said adjustable stop, means on said blade operably extending outwardly of said handle for shifting extent within said groove, and said blade being provided with at least one knife edge.

4. The letter opener according 3 wherein said blade is provided with an opening the rear edge surface of which constitutes a stop surface, said adjustable stop comprising an eccentrically mounted disk having one bearing pin pivotally mounted in said handle and having another bearing pin with means for adjusting said stop from outside said handle.

5. The letter opener according to claim 3 wherein said blade is provided with double knife edges effective for cutting in either of both directions of said guide groove.

6. The letter opener according to claim '3 wherein said blade is provided with two knife edges terminating in a knife point and extending at an angle relative to one another.

References Cited UNITED STATES PATENTS 2,291,294 7/1942 Holste 30-294 3,118,228 1/1964 Adams 30-294 3,171,201 3/1965 Carifi 30-335 OTHELL M. SIMPSON, Primary Examiner 

